1. Field of the Invention
The subject invention relates to a mounting assembly for a wheel suspension system of a vehicle wherein the mounting assembly has an insulator for isolating and/or translating movement of the wheel suspension system.
2. Description of Related Art
Mounting assemblies for wheel suspension systems of vehicles are well known in the art. Examples of such mounting assemblies are shown in U.S. Pat. Nos. 4,434,977; 4,478,396; 5,248,134; 5,330,166; 5,975,505; 6,076,794; and 6,260,835. Each of these mounting assemblies include a rigid support structure mounted to a chassis or frame of a vehicle. A piston rod extends from the wheel suspension system through the support structure. One or more insulators couple the piston rod to the support structure and allow for small relative movement of the piston rod to the support structure. The insulators also isolated the vibrations of the piston rod during an application of a force from the wheel suspension system, without causing excessive displacement.
The prior art mounting assemblies typically include at least one insulator abutting the support structure and surrounding the piston rod. Also, a jounce bumper is typically disposed about the piston rod to isolate and/or transmit intermittent high amplitude movements of the wheel suspension system. The prior art insulators and jounce bumper are frequently formed of an elastomeric rubber or cellular polyurethane material.
Many of these known mounting assemblies can fall into one of two categories, which are a single path design or a dual path design. Examples of the single path design are shown in the '166, '505, and '794 patents. In the single path designs, the jounce bumper rests in a steel cup that forms a bottom plate of the assembly. The jounce bumper in this design is able to pivot along with the piston rod and can be formed of a relatively thick wall, which increases durability of the jounce bumper. An insulator is disposed on each side (top and bottom) of the support structure above the jounce bumper surrounding the piston rod. Small amplitude vibrations or displacements of the piston rod are isolated by the insulators. Intermittent high amplitude movements of the wheel suspension system are isolated and/or transmitted by the jounce bumper and insulators.
It would be preferred that the insulators be formed of a low density material to maximize the isolation characteristics. However, due to the configuration and positioning of the insulators in the single path design, the large loads due to intermittent high amplitude movements of the wheel suspension system are also transmitted through the insulators. The insulators must therefore be molded of a high density material to withstand these large loads. As a result, the small amplitude vibration or displacement isolation characteristics are diminished.
In the dual path designs, the jounce bumper rests in a cup that is rigidly fixed to the support structure. An example of a dual path design is shown in the '396 patent. The piston rod is connected to an insert enclosed by a single insulator. As in single path designs, small amplitude vibrations or displacements of the piston rod are isolated by the insulator. However, unlike the single path design, the intermittent high amplitude movements of the wheel suspension system are only isolated and/or transmitted by the jounce bumper directly into the support structure. Hence, the insulator can be formed of a lower density material for improved optimization of isolating the small amplitude vibrations of the piston rod.
Although the dual path design has some improved performance characteristics over the single path design, the dual path design has its deficiencies. For example, the jounce bumper in the dual path design typically does not move with the piston rod. As such there must be a greater clearance between the piston rod and the jounce bumper. This in turn requires that the jounce bumper have a thinner wall which can affect durability. In addition, the dual path design is more difficult and more expensive to manufacture than the single path design.
Accordingly, it would be desirable to develop a mounting assembly that captures the advantages of both the single and dual path designs while avoiding the deficiencies with these designs.